Community Structure and Seasonal Succession of Phytoplankton in Yudong Reservoir of Yungui-plateau
云贵高原渔洞水库浮游植物群落结构及季节演替

The community structure and seasonal succession of phytoplankton were investigated every month from November 2009 to October 2010 in the Yudong Reservoir,Zhaotong City,Yunnan Province.A total of 96 phytoplanktonic algal species belonging to 7 phyla were identified,including 52 species of Chlorophyta,22 species of Bacillariophyta,13 species of Cyanophyta,3 species of Pyrrophyta,and 2 species each of Cryptophyta,Chrysophyta,and Euglenophyta.The biomass of phytoplankton in the reservoir was lower in winter and spring that in summer and autumn.The peak cell density of algae was 1.19×107cells/L in August and the peak chlorophyll-a concentration was 28.6 μg/L.The dominant species in the reservoir were Fragilaria capucina Desm.and Synedra acus Kütz.of the Bacillariophyta at all times of the year,in addition,Ceratium hirundinella(müll.) Schr.of Pyrrophyta and Dinobryon divergens Imh.of Chrysophyta were subdominant species from March to May.The relationship between seasonal succession of phytoplankton and environmental factors was analyzed by using redundancy analysis(RDA).The result showed that the most important factor was water temperature.Water temperature presented a significant positive correlation with biomass of phytoplankton in the reservoir(r=0.762,P<0.01),but a significant negative correlation with phytoplankton species(r=-0.721,P<0.01),and a negative correlation with diversity index(r=-0.638,P<0.05).